In many situations, color video is transmitted down long lengths of coaxial or twisted-pair cable. Cable losses vary depending on the cable length between a video source and a display device. If left uncompensated, cable losses will degrade the picture quality. It is a difficult process to manually adjust the cable equalization once a system, having a single video source with multiple display devices, has been installed in an aircraft.
The problems of cable equalization have been addressed in the past in various yet undesirable ways, including (1) keeping the cable lengths short, so that cable equalization is not required; (2) an alternative approach for longer cable lengths is to provide a fixed amount of amplification that overcompensates short cables and under-compensates long cables, which improves the picture quality at long lengths, while degrading it somewhat at short cable lengths; and (3) manually adjusting the cable equalization for each remote display device after system installation.
Therefore, in order to eliminate the shortcomings of each of the three attempted "solutions" described above, it is an object of the present invention to provide a system that allows cable equalization to be tailored for the specific cable lengths on a particular model of an aircraft.
It is a further object to provide a system in which the cable equalization amplification function required for each remote video display device can be set remotely by a centrally-located system controller during the system initialization.
It is a still further object to provide a system in which the programming information required to initialize the cable equalization amplifier in each remote video display device can be stored in a memory device in the centrally-located system controller, which eliminates the need to manually set amplification values in the remote video receiver.